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Characterisation of cellulase activity in the digestive system of the redclaw crayfish (Cherax quadricarinatus) |
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| Authors: | Xiao M Xue Alys J Anderson Neil A Richardson Alex J Anderson Gang P Xue and Peter B Mather |
| Institution: | a School of Natural Resource Sciences, Queensland University of Technology, GPO 2434, Brisbane, QLD 4001, Australia b Centre for Molecular Biotechnology, Queensland University of Technology, GPO 2434, Brisbane, QLD 4001, Australia c CSIRO Tropical Agriculture, 306 Carmody Rd., St. Lucia, QLD 4067, Australia |
| Abstract: | Endogenous cellulase activity was identified in the gastric fluid and digestive gland of the redclaw crayfish. Cellulase showed maximal activity from pH 4 to 5 and was stable for up to 2 h at 40°C. Cellulase activity in the digestive gland was unaffected by antibiotic treatment. Taken together these findings suggest a significant endogenous component for redclaw cellulase activity. Partial purification of cellulase activity was performed using anion exchange and gel filtration chromatography. One major and one minor band of activity were identified subsequently by SDS-PAGE and zymography. The molecular weight of the major band was estimated at 40 kDa while the minor band was estimated at 30 kDa. Redclaw cellulase enzymes demonstrated broad substrate specificity, hydrolysing polysaccharides containing β-1,4 and mixed β-1,4 and β-1,3 glycosidic bonds but showed a preference for soluble substrates. Hydrolysis products of cellodextrins of various lengths also showed that the enzymes liberated free glucose. Exposure of redclaw to antibiotics resulted in a dramatic decline in bacterial populations in the gastric contents (>90%) but only a 40% decline in cellulase activity. |
| Keywords: | Redclaw Cellulase activity Characterisation Crustacean nutrition |
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